Lapping apparatus and method



LAPPING APPARATUS AND METHOD Original Filed Sept, 16. 1937 INVENTOR By HMA@ MM@ ATTORNEY-5..

Patented Mar. 246,

UNITED STATES.

LArrlNe APPARATUS AND METHOD David A. Wallace, Detroit, Mich., assignor -to .Chrysler Corporation,

corporation of lDelaware Highland Park,'Mich., a

Application september 1s. 193i, serial No'. 164,129

Renewed April 16 claims.

'Ihis invention relates to improved apparatus. and method for lapping annular members.

Particularly, the invention pertains to improvements in the methodv of and apparatus for lapping piston rings andthe like.

f Itis an object of the invention to .provide lapping apparatus by which work can be moved relative to the lapping element and by which the means for holding the work movement is automatically released periodically to allow Athe work to expand under its inherent resiliency to 'K substantially its final outside diameter; l

Another object of the invention resides in the provisionof apparatus of this character by, which the work may beA reciprocated` at a speedof substantiallyvibratory order while at the same time reciprocated at apslower speed and throughout a longer course and rotated about an axis extending y,

25 to allow the work to expand under its own natural resiliency to substantially its. iinal outside diameter.

A'further object of the invention is the provi` sion of lapping apparatus by which'is produced relative movementsbetween `the piece of 'work and the lapping element that is lthe result of a lplurality of dilerent component movements in excess of two components, of which each compo, nent is confined to one characteristic of the con tour desired, and by which the means for holding the work during these component movements is automatically momentarily released at the ends of one of said componentl movements to allow the work to expand under its own natural resiliency to substantially its iinal outsidediameter. Additional'objects ofthe invention reside in the provision of an apparatus of this kind by which the work can be moved relative'to anex-A .pandable segmental lapping device and by which lthe means for holding the work during this relative movement is automatically released periodically to allow the work to expand under its own natural resiliency -in step by step manner ultimately to substantially its final outside diameter, and in the provision of anapparatus of this character by which the work can be` moved relative to a solid lapping element. n Other objects and advantages of the invention will be more apparent from the following descripduring, this relative D substantially parallel to the course of said ,reci-3i? tion taken in connection with the accompanying drawing, in which:

Fig. i is a fragmentary side elevational view A,

of a lapping machine embodyingv the invention, portions of the structure being broken away and illustrated in section to show the details thereof.

Fig. 2 is a horizontal' sectional view taken Aas indicated -by the line 2--2 of Fig. l.

Fig; 3 is an enlarged detail sectional `view taken approximately as indicated by the line 3-3 of Fig. 2.

lFig. 4 is a partial side elevational view corre- ,Y

sponding to Fig. bodiment of the inv tion.

In the form of th invention illustrated in the drawing, the improved lapping apparatus comprises a-base structure` 5 on which is slidably mounted a vertically reciprocable carriage 6 held in position for vertical movement by a plate member 1.

Mounted on the base structure 5 adjacent the reciprocable carriage 6 is a tool fixture, generally indicated by the numeral 8, which is stationary with respect to the reciprocatory movement of the carriage 6.

Theflxture 8 includes a tubular vertically upstanding guide member I2 mounted on 4a horizontal iiange portion I8 of the base structure 5, and in which is provided diametrically opposite axially extending slots II. Slidably mounted in telescoping relation on the guide I2 is a'lapping tool holder l0 having apertures in its wall structure registering with the slots I I of the guide I2. A cross-pin 9 is slidablyengaged in the slots II and has its end portions fitted in the apertures of the tool holder I0. The upper end portion of the guide I2 is provided with axially extending arcuately spaced slots I4 and an upper threaded extremity 33 whichA extends thereabove and above thev tool holder Il'lwhen the parts of the structure are in the positions shown in Fig. 1..

The tool holder llllmay be reciprocated vertically to bring a lapping tool 32 hereinafter more fully described, into'operative engagement with i but illustrating another emthe work by a piston rod I3 connected at its'uppery end with the pin 9 and having apiston l5 on its lower end. The piston I5 is reciprocably mounted in a cylinder I6 attached by bolts I1 to the flange I8. A spring I9 is housed within the cylinder IB to yieldingly urge the piston I5 to its lower lstation when there is insuilicient uid pressure kbelow the piston I5 and in the cylinder I6. to oppose the spring action.

A two-way valve 20 admits duid pressure, prefan inlet passage 22 that communicates with the cylinder I6, the valve 20 also connecting the passage 22 with a relief conduit 23 to evacuate the cylinder I6. The cylinder I6 has a relief passage 24 which carries away any fluid that leaks past the piston I5.

The retaining member I0, which is slidably supported on the guide I2. has a' plurality of beveled faces 26 formed at the inner extremities of slots 21 of the member I0 which register with the slots I 4in the guide I2.- Bl'ocks 25 slidablyl mounted in the slots 21 of the member I0 also register with and extend into the slots I4 ofthe guide member I2. Each of a plurality of bolts 28, best shown in Figs. 1 and 3, extend through a vertically elongated slot 29 formed in the membei` Ill, and is threaded in an aperture of the blocks 25 respectively. Interposed between washers 30 carried 'by each bolt 26 is a coil spring 3| which `Yielciingly urges the blocks 25 against the faces 26 of the member I0.

Thelapping tool 32 includes a plurality of lapping elements of each of which is carried by one of the blocks 25 and adapted to lap the external surfaces of annular members, such as piston rings, as will presently be more apparent. Up-

Ward movement ofthe tool holder I0 to its illustrated position simultaneously Wedges allv the lapping elements 32 against the faces 26 of the tool holder I0 in proper position for the lapping operation. A spacer ring 34 and a nut 35 are threaded on the upper threaded end portion 33 of the guide I2. This ring serves to limit the upward travel of the tool holder I0 beyond its illustrated position of Fig. 1.

Work 36, which is illustrated as annular split piston rings, is reciprocated relative to the lapping tool fixture 8 by driving and control mechanism which drives a work-receiving tubular shaft 31. The shaft 31 is supported for vertical reciprocatory rotational movementsl by bearings 38 and 39 mounted on the vertically reciprocable carriage 6.

Means are provided for drvingly reciprocating the carriage 6 relative to the frame structure `5.. This driving mechanism comprises a piston rod 4D having an upper extremity which abuts against a projection 4I of the carriage 6. The lower portion of the rod 40 extends through a closely fitting opening 42 of a pressure cylinder 43 supported by the base structure 5 and carries a piston 44 which is adapted to move in .response to fluid pressure introduced through a conduit 45 into the cylinder 43. A valve 46 having'a control arm 41 is adapted to control fluid medium admitted from a supply conduit 4.8. If desired, an automatic mechanical control means may be used, instead of the arm 41, to control the fluid pressure admitted to the cylinder 43 for adjustably moving the carriage 6 vertically. When the control Varm 41 is in its illustrated position the uid does not pass through the .valve 46; when atv the position indicated at 49 the conduits 45'and 48 are placed in fluid pressure inter-communication; and when at the other indicated position 50 the fluid pressure communication between the conduits ,45 and 48l is disrupted by the valve v46 and the conduit 45 is open for iiuid passage to a discharge conduit4 5I for bleeding the cylinder 43. Any fluid that leaks. past the piston 44 will drain through a relief conduit 52.

The shaft 31 carries at its Ilower extremity the work 36 which reciprocates during the lap- "2,195,056 erably air pressure, from a supply conduit 2| to ping operation. In this embodiment the work 6 comprises annular piston rings which are journaled by the lower portion of the shaft 31,

an annular iiange 53 on the shaft 31 serving as an upper stop for the work. A vertically ad- Justable slotted clamping member is normally positioned below and in spaced relationship with the lower extremity of the shaft 31 and-has an annular ange 54 that serves as an adjustable lower stop for the piston rings. A piston rod 56 is centrally disposed within the shaft 31 and its lower extremity carries ahead portion 51 forming an adjustable holding means for the clamping member 55,'as will be presently more apparent. The clamping member 55 has a slot 55a to permit the work to be installed on or removed from the shaft 31 when the work and the lapping elements 32 are out of lapping receiving relationship. When th'e work is to be installed or removed under this condition the members 51 and 55 are lowered with respect to the work and the member 55 is removed from the rod 56 by means of the slot 55a, and the piston rings are then dropped over the member 51 without receiving surface scratches from the lapping and work clamping mechanisms.

Rotation is imparted to the shaft 31 by a prime mover 58 carried by the carriage 6. A driving shaft 59 of the prime mover 58 is in driving engagement with a. gear 60 splined at lI on the shaft 31` A relatively short reciprocatory lapping movement is imparted to the Work 36, independently of the vertical position of the carriage 6, and independently of vertical reciprocatory movement of the carriage 6. This movement is produced by a yoke lever member 62 pivotally mounted at 63 on the carriage 6.' One extremity of the member 62 has an opening inwhich is journaled a hollow extension 64 of the shaft 31. This extremity of the lever 62 is confined between a. shoulder 1I on the shaft 31 and a nut member 10 threaded on the upper end of the extension 64. 'I'he other extremity of the lever 62 is pivotally connected at 65 to a link 66 which is pivoted at 61 to an eccentric carrying member 68 carried by a disc 61 which is driven by a prime mover 69 carried by the shiftable carriage 6..' As the prime mover 63 drives the eccentric member 68 the work supporting shaft 31 is.

reciprocated in' relatively short strokes by the member 62 independently ofthe vertical position of the carriage 6.

It is desirable in the illustratedv embodiment' of the invention to momentarily release the piston rings 36 to allow the rings to expand by their inherent resiliency substantially to an outer diameter desired when the lapping operation is completed. .Ihe piston rings may be con- Veniently automatically clamped and released by operating the rod 56 winch controls the clamping member 55 by fluid pressure mechanism. The

vto permit rotation of the shaft 31 and its extension 64 relative to the cylinder 14 which is held against rotation by a pin 8U mounted in the wall of the cylinder and engaged in a notch in so located with respect cylinder I6 to the relief the 'upper end post 82- mounted on the carriage 6.

Disposed in the cylinder 14 is piston 11 which is fixed to theupper; portion of the rod 56. A spring 18 bears between the upper end wall of the cylinder 14 and the piston" 11 so as to-normally urge the/piston 11 and the rod 56 downwardly. The piston 11 is normally urged upwardly by fluid under pressure admitted to the interior of the cylinder 14 through a supply pipe 18 and under ythe control of a valve mechanism therein.

Releasing of the work clamping mechanism isV produced by automatically exhausting fluid pres- Y the cylinder sure, preferably air pressure, from 14 is provided with an outlet duit 83 with a' valve casing. 85 of a one-way valve mechanism which includes `a reciprocable valve element '84. This valve casing 85 hasan outlet 86 leading to atmosphere through which 'the flow ofair is controlled by the valve element 84. 'Phe valve. element 84 may be adjusted so as to relieve pressure r,from the interior of the cylinder 14 in any suitable manner but preferably .in timed relationship with respect to the operation of the devicej In the apparatus' shown in the drawing, this is conveniently accomplished by providing a coil spring 81 between the inner end of the valve element 84 and the Yend o f the passage in the valve casing 85 in which it is mounted to normally urge the valve outwardly toward its closed position. A roller 88 rotatably mounted on the Outer-end of the valve element 84 rides upon the disc 61' -on which theeccentric carrying member v88 is mounted. The eccentric carrying' member 88 preferably has-projections v88 extendin'g outwardly fromthe extremities thereof which are adapted to engagethe roller 88 and depress the valve element 84 against the action of' the spring 81 in order to bring the valve element into open position twice during each rotation 'of the disc 61. The projections 88 are preferably. n to the crank pin 61 of the reciprocating mechanism as to cause the valve 84 to open when the shaft 31 is at its respectively opposite ends of its short reciprocatory stroke, thereby releasing lthe work at' thev ends of the short reciprocatory strokes imparted theretoby the shaft 31. l

With reference to the bodiment of the invention,

operation of this emwhen it is desired movers 58 and 88 are shut off and 'fluid pressure, preferably air pressure,

conduit 23 to permit the spring I8 to force the piston I5 downwardly and thereby to move the tool'holder I8 away from its illustrated position. Fluid pressure, preferably air pressure', is also admitted from the 'supply conduit 48, by selective manipulation of the control arm 41, to the cylinder-43 to cause the piston 44 to move the carriage 8 wardly sufllciently to take the `work out of lapping receiving relationship with the lapping elements 32. Then the uid pressure in the cylinder 14 l is exhausted by opening the valve 84, preferably manually, or by cutting oil the.supply of air through pipe 18, so as to allow thespring 18 to force the piston 11 andthe piston rod 56 downwardly to lower the members. 55'and 51 -with respect to the lapped piston rings. Tire member 85 `may then be removed entirely from-the rod may be dropped of! the portion of a vertically upstanding member 51 without receiving any surface Amarks a reciprocable upwardly catory travel to the carriage to also reciprocate with the` from the shaft 31 the prime is exhausted from the and ythe 'shaft '31 upconstruction vhave ping elements rlapping tool collar 88. The annular lapping member l be removed by unscrewing the collar 88 from the from the lapping or the work clamping mecha nisms. When the tool holder, I8 is in its lewe; position the lapping element carrying blocks 25 are noi held against the surfaces '26 of the member'I8, and the lapping elements 32.may be removed if desired for any reason.

lFollowing the unloading of after the completion of the lapping operation, to be lapped are slipped over illustrated, and the member 55 is then positioned relative to the r'od 56 by means of the slot 55, The valve 84 is, then preferably closedmanuallyto cut off exhausting of fluid pressure-from the' cylinder 14 so as to urge the member 51 into clamping engagement with the work clamping member 55. Fluid the member 51, as

the piston rings to the cylinder I6 to force' the work holder I8 to again place the work in lapping receiving relationship with the 82. This upward movement of the holder lI8 to its illustrated position of Fig. 1 wedges each of thel lapping elements 32 against the surface 26 of the holder I8. l n v The prime movers 58 and 68 are then started to respectively rotate the work carrying shaft 31 and to oscillate' in short strokes through the. pivoted memberv 62 the shaft 31. As the projections'88 of the rotating eccentric carrying member 68 contact the valve roller member 88, the fluid pressurewithin the cylinder 14 is relieved to allow the piston rod 56 andhead portion 5'1 to be urged downwardly by the spring 18- to release the piston rings 36 at the ends of each of these short reciprocatory strokes. This perioditl'ieir inherent resiliency to subexpand under stantially an outer diameter finally desired.

lWhile the prime movers 58 and 68 are in operation it is desirable `to control the carriage 6 by imparting comparatively long vertical reciproto cause the work carrying shaft v31 carriage while maintaining the piston rings 36 in lapping contact with the lapping elements 32.

lapping elements v This reciprocatory movement of the carriage 6A is preferably controlled by alternately admitting fluid pressure from the conduit 48 to the cylinder 43 and from the cylinder 43 to the discharge conduit 5I by selective manipulation of the control arm 41.. The piston rings 36 will thereby be simultaneously rotated and also reciprocated in short and long strokes during the lapping operation, resulting in a very e'mcient lapping apparatus.

Referring now to the modified embodiment illustrated in Fig. 4, another form of piston ring lapping element is shown.` It will be understood that this modified .construction is .intended to' be substituted for the corresponding parts previously described and the entire mechanism and the operation f the same will not again be duplicated. Parts of similar function been indicated by primed reference characters. n Attention is directed to the fact that the lap- 32 of the foregoing embodiment of the invention have been eliminated and in their place is a single vannular lappingmember- 32 which is detachably secured in place by a recessed guide extension I2' .and a threaded 82' may internally threaded guide extension I2'.

but different` a I ,and reciprocated in short and long strokes, as

previously described, while bearing against the annular 'lapping member 32'. 'The clamping member is periodically lowered in the same manner` a's was earlier described for lallowing the piston rings to expand under their inherent resiliency to substantially their desired final outerV diameter. l y f The illustrated lapping apparatus. is equally adapted to use segmental lapping elements, as illustrated in the foregoing embodiment, or a single, annular lapping membenfor convenience as desired without necessitating any major4 fchanges in the lapping apparatus.

, -By virtue' of the foregoing lapping apparatus and method the piston rings and` other generally cylindrical articles can be accurately brought to a true cylindrical contour and provided with i a mirror-like` iinish by intermittently permitting the article being operated upon, particularly piston rings, toexpand during lapping operation under their inherent spring action. The diametrical dimensions of the rings may be closey held to selective predetermined values.

Various modifications and changes may be effected in the illustrated applications without departing from the spirit of thelinvention or from the scope of the appended claims.

What I claim is: l

1. Apparatus for lapping an annular split member having a tendency when contracted to resiliently expand toward its normal relaxed contour comprising a support, means v.on said support for rotatably supporting and drivingly ro-4 tating the Work including members Vfor releasably holding said workgagainst expansion from a contracted condition, a tooll xture mounted on said K `said reciprocatory support4 including a lapping element engageablefy with said work, and means for releasing said.-

members of said rotatablework supporting means aieaose work to expand toward reciprocable and rotatable relative to said carriage about an axis extending generally in the direction of said reciprocable movement of said of its reciprocatory during rotation of said work thereby to allow said work to expand Qtoward said lapping element under its natural resiliency.

2. Apparatus forl lapping an annular split 'member having a tendency when contracted to resiliently expand toward its normal relaxed contour comprising a support, a carriage shiftably mounted on said support, means on said support for rotatably supporting and` drivingly rotating` the work about an axis substantially parallel to the direction oi' shifting movement of said carriage including members i'orreleasably,v holding/ said work against expansion from a contracted condition, a tool xture mounted on .said `support including a lapping element engageable with said work, and automatic means for periodically releasing said members of said 'rotatable workv supporting means Aduring rotation and reciprocation of said work to allow said work to expand toward said lapping element under its natural resiliency. j L

, `Ii. Apparatus for. lapping an annular split member having a tendency when contracted ,to

resiliently expandtoward its normal relaxedcon- I -tour comprising a base structure, a lapping element, a lWork support reciprocable relative. to said base structure and rotatable relative thereto about an axis extendinggenerally in the direction of its reciprocatory movement,` said support vincluding members for releasably holding said work against expansion. from a contracted cpndition, means for -drivingly rotating and reciprocating said work support, .and means for automatically carriage, said support including members for releasably holding said work against expansion from a contracted condition, means for drivingly rotating and` reciprocating said work support at ,a speed of substantially vibratory order and for reciprocating said carriage at a lower rate in the same'direction as said work support reciprocatory movement, and means for automatically releasing said members of lsaid support periodically to allow said work to expand ytoward said lapping element. Q

5. Apparatus for lapping anv lannular split 'member having a tendency when contracted to resiliently expand toward its normal relaxed contour, .comprising a baseA structure, a lapping element, a work support reciprocable *relativeto said base structure androtatable relative thereto about an axis extending generally in the direction movement, said support includng members for releasably holding said work against expansion om a contracted. condition, means for drivingl rotating and reciprocating said work support, nd means operable in timed relationship to said reciprocatory movement of said work support to automatically release said mem bers oflsaid work support at least at one end of stroke of said work support to allow said work to expand toward said lapping element.

6. IApparatus member having resiliently expandtowa'rd its normal relaxed contour comprising a base structure, a lapping elefor vlapping an annular split said support periodlf a tendencyvwhen contracted to ment, a work support reciprocable relative to said base structure 'and rotatable relative thereto about an axis extending vgenerally in the direction of its reciprocatory movement, said support includ,- ing members for releasably holding said work against expansion from a contracted condition, a

' sure responsive meansv for releasing said mem-- rotatable eccentric adapted to impart said reciprocatory movement to said work, means for drivingly rotating said `work support,V and iluid presbers oi' lsaid support periodically in response to rotation of said eccentric to allow said'work to expand toward saidv lapping element.

7. Apparatus for lapping an annulari split memberhaving a tendency when contracted to resiliently expand toward its 'normal relaxed contour comprising a base structure, a vlapping lelement, a work support reciprocable relative to said ,base structure and rotatable relative thereto about an axis extendinggenerally in the direction rf its reciprocatory movement, a removable clamping jaw member, a` mandrel extending through said work support and said work having an abutment for releasably holding said jaw member vto ,ref ieasably hold vsaid work against expansion from a contracted condition, means for drivingly rotating and reciprocating said work support, and means at the end of said mandrel opposite from said jaw member to periodically release said jaw aisaoso member to allow said work to expand toward said` clamping a piece of ward `said lapping element, driving mechanism lapping elemen v 8. 'I'he method of. lapping and bringing to true cylindrical contour the exterior ol an annulary split member having a tendency when contracted to resiliently expand toward its normal relaxed contour which comprises rotatably and shiftably mounting said work for reciprocatory movement e in a course substantially parallel to its rotative axis, drivingly rotating and reciprocating said work, applying a lapping element to the external surface of said work, and alternately holding said work' agalnst'expanslon and releasing said work to allow expansion periodically during such movementsof said work.

9. The method of lapping and bringing to true cylindrical contur the exterior of an annular split member having a tendency when contracted to resiliently expand toward its normal relaxed contour which comprises rotatably and shiftablyl mounting said work for reciprocatory movement in. a course substantially parallel to its rotative axis, drivingly -rotating and ,reciprocating said work, applying a lapping element to the external surface of said work, and alternately holding said work against expansion from a contracted contour and releasing said work toV accommodate expansion thereof in timed relation to said reciprocatory movement of said work, said work being released at the ends of said reciprocatory l strokes of said wor y 1o; The method of lapping and-bringing to true the' exterior of an annular cylindrical contour split member having a tendency when contracted to resiliently expand toward its normal relaxed contour which comprises rotatably and shiftably mounting said work for reciprocatory movement in a course substantially parallelto its 'rotative axis,l drivl cating said work, applying a lapping element to the Vexternal surface of said work, simultaneously rotating said work and reciprocating said work at a speed of' substantially vibratory order while f tending generally movable reciprocating said work .ata slower speed and `throughouta longer course. and alternately hold--A in'g said work expansion and releasing said work to allow expansion periodically during such movements o! said work.

11.'Apparatus for lapping member having. a

an annular split tour comprising a bascistructure,A a plurality o! annularly arranged lapping elements supported' by vsaid. base'and forming a cylindrical passage. a work support reciprocable relative to said\base and rotatable relative thereto about an axis exin the direction oi its reciprocatory movement, said support including members tor releasably holding said work against expansion from a contracted condition, means for drivingly rotating and reciprocating a portion oi said work support within said cylindrical passage-` defined by said lapping elements and expanding saidlapping element to denne a larger cylindrical passage when said work support portion is within said cylindrical passage, and means for automatically releasing said members of said support to allow said work .to expand toward said lappingelements. 12. Lapping apparatus comprising relatively lapping element supporting umts, said lapping-element mpporting unithavinga lapninlelementandsaidworksupl'tive movement of said said units, timed relation to said relative movement of said gly rotating and reciproporting .and element supporting moving the same unit including members tendency when contracted to -resiliently expand toward its normal -relaxed-con said lapping element.

\ comprises vyieldably diameter` supporting. and work work against movement toforproducing relative lapping movement between said units, and means operable during said relaunits for intermittently releasing said clamping members.

13. Lapping apparatus comprising relatively supporting unit including members for releasably ward said lapping element,- driving mechanism for producing relative lapping movement between and means operable during and in units for periodically releasing said clamping members when said units are in a predetermined relative position.

14.` Apparatus for lapping an article having a movable lapping element supporting and work. supporting units, said lapping elementfsupporting Aunit having a tendency when deilected iroma normal relaxed conditionto returnto said relaxed conditionl comprising relatively movable lapping element supporting and work, supporting units, said lapping element supporting unit having a lapping element and. said work supporting unit including members for releasably` clamping said article against movement relative to said work supporting unit and in an unrelaxed condition such that it tends to deilect toward said lapping elements,

driving mechanism for producing relative lapping movement-between said units, and means operable during relative'movement oi saidv units for,y

intermittently releasing said clamping members for accommodating deflection of said article to-v ward said lapping element.

l5. Lapping vapparatus for lapping an article having a tendency whemdeilected from its 7relaxed condition toreturn to said condition comprising relatively movable lapping element supwork supporting units. said lapping unit including a movably mounted lapping element and mechanism for toward and away from said article to denect 4and accommodate relaxing oi said article respectively and said work supporting for releasably clamping said articlerelative tosaid and in an unrelaxed condition such that it tends to deect toward said lapping element, driving mechanism for producing relative lapping movement between said units, and means operable during relative movement oi said units for intermittentlyreleasing said clamping members for accommodating denection ofs'aid article toward 16. 4The method of urging 'a surface oi' said article againstr a lapping element, releasably clamping, said articleu against further movement toward saidv element while it is yieldably urged thereagainst to positively hold said surface in a predetermined relationship article, drivingly producing. relative lapping movement between said article and said lapping element, and intermittently releasing said article to accommodate movement of said lapping-surtace toward said work supporting unit lapping an article, which\ with respect to said lapping element during said relative 'lapping movement and in a predeter- 7.0

mined timed relationship with respect thereto.

pavmaswmo'n.

10. lapping element and said work L 

